1. Field of the Invention
The present invention relates to a method for manufacturing a color filter applicable to a color liquid-crystal display used for a color television, a personal computer, a car navigation system, a small-size television or the like, and to a liquid-crystal device using a color filter manufactured by the method.
2. Description of the Related Art
Recently, in accordance with development of personal computers, particularly, portable personal computers, there is an increasing demand for liquid-crystal displays, particularly, color liquid-crystal displays. However, in order to realize further diffusion of such displays, it is necessary to reduce the production cost of the displays. Particularly, there is an increasing request for cost reduction of color filters whose cost occupies a considerable part of the cost of the displays.
Various approaches have been tried in order to respond to the above-described request while satisfying characteristics required for color filters. The first task in color-filter manufacturing methods is to uiformly color each pixel (a colored portion) of a color filter. Namely, it is necessary to make the amount of a coloring material per unit area for each pixel uniform.
Conventionally, in a pigment dispersion method which is widely used as a color-filter manufacturing method, the amount of a coloring material per unit area of a colored portion is made uniform by making the thickness of a film forming the colored portion constant. Recently, color-filter manufacturing methods according to an ink-jet method have been proposed, and various proposals for making the degree of coloring for each pixel uniform have been provided, for example, in Japanese Patent Laid-Open Application (Kokai) No. 9-281324 (1997), and the like. More specifically, the amount of discharged ink from each nozzle is obtained by discharging in advance ink from nozzles of an ink-jet head onto a medium, and the amount of supplied ink per unit area in the entire colored portion of a color filter is made constant based on the obtained result.
The assignee of the present application has proposed a method for making an optical effect of each pixel uniform. This method intends to reduce unevenness in color which is considered occur due, for example, to a difference in the distribution of coloring within a pixel depending on a position within a colored region. The optical effect indicates the density of coloring of a pixel. More specifically, the optical density is a physical amount related to the density of coloring. It is considered to be rational to use the radiant flux of light passing through each pixel when projecting light in the same condition as in the actual state of use of the concerned color filter as this physical amount. Actually, although illumination for a color filter is not entirely identical for each pixel, the illumination may, in many cases, be dealt with as substantially identical. In such cases, the radiant flux of light passing through each pixel for a constant amount of incident light is used as the above-described physical amount.
However, when measuring the radiant flux of light passing through each pixel in order to make the optical effect uniform, if the area of an aperture of a black matrix differs, the radiant flux of light passing through a pixel differs and therefore the optical effect differs even for the same density of coloring. Accordingly, even if coloring conditions are corrected so as to provide a uniform optical effect in the measured color filter, the optical effect differs when the area of an aperture of a black matrix differs in a color filter to be newly colored.